Scotland's senior law officer has denied challenging the finding of a Ministry of Defence board of inquiry which blamed pilot error for a helicopter crash in which 29 people died.

Lord Advocate, Colin Boyd QC, was reported to be at odds with the MoD over the tragedy on the Mull of Kintyre in 1994.

It followed the publication of a letter written by Mr Boyd to a member of the Scottish Parliament.

Mr Boyd had been asked to re-open the fatal accident inquiry at which a sheriff ruled there was not enough evidence to blame the two pilots for causing the crash on the Mull of Kintyre in 1994.

Colin Boyd, QC: Challenging MoD view

The MoD board pinned the blame on the two pilots, who were among those who died, but a campaign has been fought to overturn the finding and clear the men's names.

The magazine, Computer Weekly, has persistently reported that it has new evidence pointing to faulty computer software, known as Fadec, on the helicopter.

In his letter to the SNP's Kenny MacAskill, Mr Boyd said: "Having regard to the findings of the sheriff, Crown counsel considered that, even if the new information could be substantiated in an inquiry process, it is highly unlikely that the findings of the sheriff would be different.

"Indeed, insofar as the new information about Fadec invites speculation as to another possible cause for the crash, it may be thought to reinforce the sheriff's inconclusive determination as to the cause of the accident."

Inquiry ruled out

In a statement on Wednesday, Mr Boyd stressed that his letter did not imply any comment on the MoD finding of pilot error.

It made plain that the determination by the RAF was a matter for the Ministry of Defence, not for him. His sole purpose in writing the letter was to rule out a further inquiry.

Mr MacAskill said he accepted Mr Boyd's stance but that he now wanted the MoD's actions investigated.

He said: "We were not told by the Ministry of defence about the Fadec system.

"They simply did not tell us that and at the same time that was going on they were litigating against and suing the manufacturers of Fadec in the United States.

"Secondly, we had an elected government minister in Malcolm Rifkind saying he doesn't think he was given proper information or that he was properly advised."

Armed Forces Minister John Spellar said Mr Boyd's remarks had been misinterpreted.

Computer software is said to have been at fault

"These bits of evidence do not undermine the fundamental issue of where the plane was. It was flying too fast, too low and into fog," Mr Spellar told BBC Radio 4's Today programme.

"If there's real new evidence, we've always said we would look at it."

Mike Tapper, father of one of the pilots, Flt Lt Jonathan Tapper, accused the MoD of dismissing any new evidence out of hand.

"It seems that the government would rather protect the elite within the MoD than to protect natural justice," he said.

Intelligence experts

Twenty five senior police and intelligence officers based in Northern Ireland plus two other air crew were also killed.

Supporters of the pilots, who include former defence ministers, RAF officers and an ex-law lord, believed it could provide a major boost for their campaign.

The MoD also refused to reopen the investigation into the tragedy last month, despite a report casting doubt on the inquiry verdict and suggesting four possible causes of the accident.

The paper, by three fellows of the Royal Aeronautical Society, said there could have been a runaway engine caused by a computer fault; a failure in the system that controls the helicopter's rotors; loss of control due to contamination of the hydraulic system; or a physical jam in the control mechanism.